Dave,
This might sound either a bit radical or a bit lazy; or possibly even a bit opportunistic; but, I know of someone who punched a hole in the belly by dropping a phillips screwdriver point first- glued on a drain hole grommet, cleaned up the center hole with a fine point soldering iron, called it a drain hole and then measured and put in a matching one on the opposite side so it looked like it was planned that way.........
Please don't ask me how I know this.
Dave S
KF7 Trigear